射孔工况下多喷嘴水力喷射工具冲蚀研究

Study on erosion of multi-nozzle hydraulic jet tools under perforation condition

大排量高砂比水力喷砂压裂的射孔过程中,高速流动的携砂液会对喷射工具表面产生严重的冲蚀损伤。根据喷射工具本体材料35CrMo钢的喷射式冲蚀实验,得到了半经验的冲蚀计算模型。结合DPM数值模拟方法获得射孔过程中工具内部的液固两相流场分布及壁面冲蚀速率,讨论了液相参数和固相颗粒参数对流经上、下游喷嘴颗粒含量及喷嘴入口区域冲蚀损伤的影响。计算结果表明,当工具内部流动达到稳定时,下游喷嘴的颗粒含量大于上游喷嘴的颗粒含量,下游喷嘴入口区域的冲蚀损伤更为严重,颗粒含量及冲蚀损伤的差异性在使用大排量、高黏度液体和大直径、高密度颗粒时更为严重。为防止因上、下游喷嘴颗粒含量差异较大影响射孔效率的情况,建议在实际生产过程中,使用携砂性较好的高黏度压裂液和低密度小直径的颗粒,在保证作业效率和工具寿命的同时控制施工排量。

During the perforation operation of hydraulic sand blasting fracturing with large displacement and high sand ratio,sand-carrying fluid flowing at high speed will cause serious erosion damage to the surface of the jet tool.Based on the jet erosion experiment on35CrMo steel,which is the body material of the jet tool,a semi-empirical erosion calculation model was obtained.Combining with DPM numerical simulation method,the distribution of liquid-solid two-phase flow field and the wall erosion rate in the tool in the perforating process are obtained.The effects of liquid and solid particle parameters on the particle content when flowing through the nozzles at upstream and downstream and on the erosion damage at the inlets of the nozzles were discussed.The results show that the particle content in downstream nozzles is larger than that in upstream nozzles when the flow inside the tool remains stable,the erosion damage at the inlet of downstream nozzles is more serious,and the difference of particle content and erosion damage is more serious when using high viscous liquid with large displacement and large-diameter particles with high-density.In order to prevent the perforation efficiency from being greatly affected by the difference of particle content between in upstream and in downstream nozzles,it is recommended to use high-viscosity fracturing fluid with good sand-carrying property and small-diameter particles with low density in the actual production process to control construction displacement when guaranteeing operation efficiency and tool life.